Electrical induction apparatus



July 1, 1930. M. UNGER 1,769,871

ELECTRICAL INDUCTION APPARATUS Filed Oct. 21, 1929 Fig.5

' Fig.5.

@ /4 "'"Inum Inventor-*1 M agnus Linger YWI/QZZM H i s Attovney Patented July 1, 1930 UNITED STATES MAGNUS UNGER, F PITTSFIELD, MASSACHUSETTS, ASSIGNOR '10 GENERAL ELECTRIC PATENT OFFICE COMPANY, A. CORPORATION OF NEW YORK ELECTRICAL INDUCTION APPARATUS Application filed October 21 1929. Serial lie-401,329.

6 of this type, such as transformers and reactors, are generally built up' of superposed sheets of magnetic material, the sheets being insulated from each other to reduce losses due to eddy currents. There are, however,

always some losses due to eddy currents and hysteresis and these losses appear as heat. The very large cores are frequently formed with ducts through which a cooling medium such as air or oil may flow. The cooling medium will carry away the heat from the interior of a core and thus prevent excessive internal temperatures. The general object of the invention is to provide an improved magnetic core construction with a duct through which a cooling medium may flow.

The invention will be better. understood from the following description taken in connection with the accompanying drawing in which Fig. 1 is a perspective view of a mag-' netic core constructed in accordance with the invention, the particular core shown being of a form commonly used in transformers and reactors; Fig. 2 is a cross-sectiona view on the line 2-2 of Fig. 1, and Figs. 3,

4 and '5 are explanatory views showing details of construction.

Like reference characters indicate similar parts in the different views of the drawing.

The magnetic core 10 shown in Figs. 1 and 2 of the drawing is built up of superposed sheets of magnetic material which ma be insulated from each other by the sca e formed on their surfaces during an annealing process before they are assembled. The sheets or laminations are held together in assembled relation by bolts 11 which may be of insulating material to avoid short circuiting of the laminations.

A duct 12 through the interior of the core is formed by separating two of the inner laminations 13 which are spaced apart by small insulating spaces 14. Each spacer 14 is in the form of a small disc or button with a central aperture which fits over a tongue 15 out or punched along its side edges and outer end from one of the sheets 13 and bent along its inner end to project integrally and at substantially a right angle from the sheet. The insulating spacers 14 may be punched from sheets of insulating material or they ma be formed by cutting off the pro er .lengt s from the end of an insulating liollow tube having a bore of a diameter such as to fit tightly over the tongues 15.

I The tongues 15 may of course be formed on either one or both of the laminations 13. Each of these tongues is preferably tapered slightly toward its outer end which is preferably slightly narrower than the diameter of the bore or aperture in the spacer, the inner end or base of the tongue being slightly wider than the aperture in the spacer so that the spacer will be held firmly in place when pressed over the tongue and against the surface of the lamination l3 surrounding the tongue. The spacers 14 with their supporting tongues 15 should be spaced closely enough to prevent such bulgin of the laminations 13 as to restrict the not 12 objectionally. The length of each tongue 15 should be less than the thickness of its l spacer 14, as shown in Figs. 4 and 5, so that it cannot short circuit the two laminations 13 and cause objectionable circulating eddycurrents.

The magnetic core of a transformer or other piece of induction apparatus is frequently grounded and it may be desirable in some cases to form one or a few of the spacers 14 of conductive metal so that the whole core may be grounded by a single external ground connection. In case more than one spacer is of conductive material, however, it is desirable that they be widely separated to avoid objectionably large eddy currents.

The invention has been explained by describing and illustrating a single form and application thereof, but it will be apparent that changes may be made without departing from the scope of the invention as covered by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is 1. A magnetic core for electrical induction apparatus, said core being formed of superposed magnetic laminations, two adjacent inner laminations being separated by spacers to form an internal duct in the core, one of said inner laminations having projecting tongues engaging the spacers to maintain the spacers in predetermined relative positions.

2. A magnetic core for electrical induction apparatus, said core being formed of superposed magnetic laminations, two adjacent inner laminations being separated by spacers to form an internal duct in the core, one of said inner laminations having integral projecting tongues engaging the spacers to maintain the spacers in predetermined relative positions.

3. A magnetic core for electrical induction apparatus, said core being formed of superposed magnetic laminations, two adjacent inner laminations being separated by perforated spacers to form an internal duct 1n the core, one of said inner laminations having tongues projecting into the perforations in the spacers to maintain the spacers in predetermined relative positions.

4. A magnetic core for electrical induc tion apparatus, said core being formed of superposed magnetic laminations, two adj acent inner laminations being separated by perforated spacers to form an internal duct in the core," one of said inner laminations having tapered tongues projecting into the perforations in the spacers to maintain the spacers in predetermined relative positions, said tongues being narrower at their outer ends and wider at their bases than the apertures in the spacers.

In witness whereof, I have hereunto set my hand this seventeenth day of October,

MAGNUS UNGER. 

